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RE: [Xen-devel] [patch] 32/64-bit hypercall interface revisited

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, "Hollis Blanchard" <hollisb@xxxxxxxxxx>
Subject: RE: [Xen-devel] [patch] 32/64-bit hypercall interface revisited
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Wed, 26 Apr 2006 16:15:08 +0800
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, xen-ppc-devel@xxxxxxxxxxxxxxxxxxx
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Thread-topic: [Xen-devel] [patch] 32/64-bit hypercall interface revisited
>From: Keir Fraser
>Sent: 2006年4月26日 15:50
>On 25 Apr 2006, at 21:24, Hollis Blanchard wrote:
>Also, no need to use GET_GUEST_HANDLE() in the libxc's
>function. Xen will never update the buffer pointer these days -- it
>always fills the buffer from the start. When we eventually kill the
>mlock() crap and implement it properly, I think GET_GUEST_HANDLE()
>be killed off entirely.
>  -- Keir

Hi, Keir,
        Could you reveal something about how to kill mlock() completely?
:-) Current mlock() can ensure the ptes related to user buffer existing 
in page table, and thus xen can copy from/to that buffer directly. By 
removing mlock(), do you mean page fault may be injected to guest 

        On xen/ia64, the hypercall parameter copy has been an issue 
for a long time, since xen/ia64 only caches virtual TLB and doesn't 
walk guest page table. Even mlock() can't ensure 
copy_from/to_guest successful. People are considering either 
injecting page fault to guest and then resume the hypercall, or 
lock parameter pages by using similar mechanism like PPC's 
proposal. So we're interested in your idea to see whether applicable 
to xen/ia64.


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